1. Field of the Invention
The present invention relates to a lamp unit of a vehicle headlamp, and particularly, relates to a projector-type lamp unit that uses a light-emitting element as a light source.
2. Related Art
In recent years, even in vehicle headlamps, lamp units that use a light-emitting element, such as a light-emitting diode, as a light source have been adopted.
For example, Patent Document 1 discloses a so-called projector-type lamp unit including a projection lens arranged on an optical axis extending in the longitudinal direction of a vehicle, a light-emitting element arranged so as to face upward behind a rear focal point of the projection lens and in the vicinity of the optical axis, and a reflector arranged so as to cover the light-emitting element from above and to reflect the light from the light-emitting element forward toward the optical axis.
In such a case, in the lamp unit disclosed in Patent Document 1, a mirror member that has an upward reflecting surface that upward reflects a portion of the reflected light from the reflector is provided between the reflector and the projection lens, and a light-emitting element that has a plurality of light-emitting chips arranged so as to be adjacent to each other in the vehicle width direction is used as the above light-emitting element.
[Patent Document 1] JP-A-2006-335328
In the projector-type lamp unit provided with a mirror member as disclosed in the above Patent Document 1, the utilization efficiency of the light from the light-emitting element can be enhanced, and thereby the brightness of a light distribution pattern can be formed sufficiently.
However, in the projector type lamp unit, a light source image formed on the rear focal plane of the projection lens is projected onto a virtual vertical screen ahead of the lamp as an inverted image. Thus, when a light-emitting element having a plurality of light-emitting chips arranged so as to be adjacent to each other in the vehicle width direction is used as the light source, a light source image formed by the reflected light from a central reflection region close to and just above the optical axis in the reflector has a gap between the light-emitting chips. Because of this, there is a problem in that the gap may be projected as a longitudinally striped dark portion, and thereby light distribution unevenness may be caused in a light distribution pattern.